Image Dithering Tool

Dithering fakes colours a palette does not have by mixing the ones it does, the way newspapers, early computers and handheld consoles drew photos. This tool reduces an image to a small palette — 1-bit black and white, greys, Game Boy greens, CGA, EGA, web-safe or your own colours — and spreads the difference with one of twelve classic methods. Use it for retro art, e-ink and thermal printers, laser engraving or tiny file sizes. It runs in your browser.

How to use this tool

1. Choose one or more images.
2. Pick an algorithm: Floyd–Steinberg for smooth results, Atkinson for crisp contrast, Bayer for a regular cross-hatch.
3. Pick a palette, and set the brightness shift if the result is too dark or too light.
4. Choose a pixel size above 1 for a chunky look, then download the PNGs.

Formula

error diffusion: e = value − chosen palette colour; each later neighbour += e × weight ÷ divisor (Floyd–Steinberg: 7, 3, 5, 1 ÷ 16)

Atkinson spreads only 6/8 of the error (1/8 to six neighbours), Jarvis–Judice–Ninke 48 parts over 12 neighbours, Stucki 42, Burkes and Sierra 32, Two-row Sierra 16 and Sierra Lite 4. Ordered dithering adds a fixed Bayer threshold ((matrix value + ½) ÷ n² − ½, times the palette step) before choosing the nearest colour; random dithering adds noise instead. Grey and Game Boy palettes are matched by brightness (Rec. 709 luma), the others by RGB distance.

Example

The top-left pixel of a blue photo, RGB (38, 99, 234), has luma 0.2126 × 38 + 0.7152 × 99 + 0.0722 × 234 = 95.8. In 1-bit it becomes black (95.8 < 127.5), leaving an error of +95.8. Floyd–Steinberg adds 95.8 × 7/16 = 41.9 to the next pixel, 95.8 × 5/16 = 29.9 to the one below, and so on, so an area of this blue ends up with roughly 38% white dots — its brightness, 95.8 ÷ 255.